Rhizomes available in August
Though they come in a great array of colors and sizes, all bearded Irises want good drainage, plenty of sun, and room to grow. For best results, newly planted rhizomes should be well-rooted before the growing season ends. This means a July through September planting season. (Stretch this to October if you have a particularly hot yard.)
Pick a spot that receives at least a half-day of sun and provides well-drained soil. Irises are adaptable to most soils, so a slight slope or raised bed can be enough even with our heavy clay (although added humus is recommended). Always plant Iris so that the top of the rhizome is exposed and the roots are spread out facing downward. It is a common mistake to plant too deeply. Leave space between the plants (usually 12 to 24 inches) so that you won’t have to dig up and divide the crowded rhizomes so frequently.
Water new plants regularly to establish, but take care not to over-water later on. Deep watering at long intervals is best—once every two weeks in most areas, less if weather is cool. Feeding depends on the soil, but high nitrogen can encourage rotting. A light application in early spring and again about a month after bloom should provide good growth and bloom.
If Irises are allowed to become too crowded, flowering will suffer and diseases may be encouraged. Thinning or dividing every three or four years at planting season will keep these potential problems in check. When rhizomes are cut, let them air dry for some hours (or overnight) to allow them to form callus. Keep Iris beds generally clean and free of weeds and debris and in late fall remove old and dry leaves.